Fuel economy of vehicles has been a thrust area of research in the global auto industry due to the depleting resources and rising fuel costs. It has been observed that drivers of vehicles use higher power than necessary under the road conditions and traffic. On the other hand it is desirable to drive vehicles based on automatically optimised fuel consumption related parameters appropriate to the road, load and environmental conditions to achieve enhanced fuel economy and vehicle performance.
Several examples in prior art have addressed such issues though with limited success.
JP H05 332236A discloses an invention that is related to the combination of engine power limitation through a switch which controls fuel injection timing map and an ignition timing map. It is to be appreciated that ignition timing is appropriate for spark ignited engines like petrol, LPG and CNG, where the throttle valve is used for controlling the air supplied to engine based on the demand. In specific terms, the invention in JP H05 332236A is related to two or more injection timing and ignition timing maps. The invention in JP H05 332236A does not provide automatic selection control in the operating mode. Further it does not provide inputs from the road gradient and load which is of immense significance in selection of the correct operating mode that impacts driveability performance and fuel consumption. The input response is only controlled through a switch and a driver's aggressive driving habit and over speeding of a vehicle cannot be restricted by the system in JP H05 332236A.
DE 10 2009 008 872 A1 discloses a method for controlling/limiting the acceleration of a vehicle. By actuating the accelerator, engine power is controlled by the engine control unit. To achieve this, different characteristics are stored in the engine control unit. The engine is mechanically connected to an automatic transmission, system controlled by a transmission control unit which is connected to the gear shifting lever. Operating modes of the gear transmission can be adjusted by the driver. In addition, a kick-down switch disposed at the limiting stop of the accelerator gets actuated with a complete pressing down of the accelerator. DE 10 2009 008 872 A1 does not provide automatic selection control of the operating mode. Specifically DE 10 2009 008 872 A1 is related to the combination of engine power limitation as well as automatic transmission shift strategy. It does not have provisions for inputs from the road gradient and load, the power limitation being removed by complete pressing down of the accelerator. Such a system has the limitation that it cannot control aggressive driving habit and over speeding of a vehicle.
EP 0110226 A2 relates to a fuel demand signal derived in accordance with selected one (A, B or C) of a plurality of functions each specifying a respective predetermined related between value of fuel command signal, corresponding to fuel flow rate, and accelerator pedal displacement. This also determines the corresponding optimum air flow rate and controls the opening of the throttle valve. The selection of the respective function defining the relationship of the accelerator pedal movement to actual fuel flow command made by the operator or driver via a selector switch provides the desired engine response characteristic. This allows the variation within a range from normal to either a faster or more conservative engine reaction. The invention in this patent is appropriate for spark ignited petrol, LPG and CNG engines. This invention does not provide automatic selection control of the selection mode with inputs from injection timing, rail pressure, road gradient which are crucial in determining correct operating mode that impacts the driveability performance and fuel economy of the vehicle.
JP03132370B2 discloses a device which has a target speed level setting unit that sets desired speed level based on detection signals from a vehicle speed detector and an engine load detector. A vehicle load degree which corresponds to the weight and inclination resistance of the vehicle is detected by a vehicle load degree calculator. The engine auxiliary brake operation is also determined by means of another detector. A speed change controller controls speed change level, shifting the target speed level to speed level which is one step lower when the computed vehicle load degree is below a predetermined value and when operating the engine auxiliary brake. It achieves enough braking force which suits driver intention especially when traversing a downhill road. JP03132370B2 is therefore related to deceleration control of a vehicle on downhill. There is no provision of the multiple operating modes.
U.S. Pat. No. 7,003,394B2 describes an engine controller that controls injection quantity or intake airflow supplied to a cylinder of an engine using vehicle level sensors and determining the demanded torque from driver. A fairly complex algorithm is used to arrive at the target acceleration resistance based on the target acceleration and the vehicle weight. Air resistance and rolling resistance are added to the acceleration resistance to determine the running resistance for accelerating or decelerating the vehicle at the target acceleration. The driving wheel torque is determined using the running resistance and a constant based on the effective tire radius. The engine output shaft torque equivalent to a driver requested torque is determined using the driving wheel torque and a constant based on the final gear ratio. There is no provision for the use of multiple map operating modes.
U.S. Pat. No. 7,967,724B2 is primarily related to two wheeler type applications describes plurality of shift maps for deriving shift timing of an automatic transmission, and a controller for selecting one shift map of said plurality of shift maps according to output signals from said plurality of load sensors, and controls the shift timing of the automatic transmission according to the selected one shift mode. The Controller switches the Shift map of a standard type to an output-emphasizing type Shift map based on the total value of loaded weight sensed by the load sensors than the predetermined time. The system has no provision for inputs from road gradient and therefore suffers from severe limitations in ensuring enhanced driveability performance and fuel economy.
U.S. Pat. No. 8,311,722B2 describes an active driver control system. Additionally, in various example embodiments, this technology provides methods for optimizing fuel economy (or energy consumption) through active compensation of driver controlled inputs. The Active Compensation functionality is used to moderate ‘sweet spot’ vehicle response with driver desired performance. In particular, the active compensation functionality can be used to smooth the vehicle response and attenuate undesired frequency content from the driver input. The system is not fail safe, has no active control or audio command to driver while driving. Further, the driver may neglect the rating provided by “Green driving index” and continue to over-speed
US 20080006711A1 relates to auxiliary engine drive control based on the demand mode of economy or normal mode. It is controlled by a demand switch for fuel economy with various blower speed control maps using inputs of coolant temperature sensor. When the economy switch signal is ON to instruct that fuel economy should be given priority, a blower of an air conditioning device is operated using a blower characteristic map for fuel economy so that a blower level of the air conditioning device is changed with respect to the change in an engine coolant temperature at a low rate. The system is not provided with any provision to control the ECU for activation of operational modes dependent on engine torque curve, injection quantity, timing and rail pressure that are crucial in the determination of driveability performance and fuel economy benefits.
PCT Application no. PCT/IN2013/000349 describes an invention related to a common rail electronically controlled vehicle provided with operation selection mode wherein the user can select either of the power mode and the economy mode of vehicle operation depending on the road and load conditions. The system neither provides for automatic selection control of the operating mode nor does it provide inputs in terms of road gradient and load to the ECU which are key determinants in the selection of the appropriate operating mode for the best fuel efficiency and driveability performance. The input response is controlled through a switch and a driver's aggressive driving habit and over speeding of a vehicle cannot be restricted by such a system. It uses only one set of Rail pressure, injection quantity & injection timing parameters for all modes.
There remains an unmet need to provide modes selected switching control for vehicle that is capable of optimizing the operating conditions based on load and gradient sensed inputs to the vehicle for the best mode of operation that would result in enhanced fuel economy and vehicle performance.
The challenge therefore lies in providing a comprehensive system involving the engine and vehicle power-train configuration that would be valid for multiple applications [e.g. high power applications, load applications, one side empty applications, under-load applications, better turnaround time applications, and their combinations depended on market demand] with best fuel economy and drivability performance.